Tow truck

ABSTRACT

A tow pin attachment for tow trucks. The attachment can be removably connected to a tow truck. A tow pin carried by the attachment is movable between operative and inoperative positions. Means on the tow pin lock the attachment to the truck when the tow pin is in operative position.

United States Patent Abram et al.

[451 Apr. 4, 1972 TOW TRUCK v Inventors: Guy R. Abram, Montreal, Quebec; Emil Oflerman, Therese West, Quebec, both of Canada Assignee: Matthew Moody Ltd., Terrebonne,

Quebec, Canada Filed: Jan. 5, 1970 Appl.No.: 537

new. ..10'4/172 BT lnt.C| ....B65g 17/42 Field of Search ..l04/l70, 172

[56] References Cited,

' UNITED STATES PATENTS 2,878,758 3/1959 DAltrvi ..l04/ 172 BT Primary Examiner-Arthur L. La Point Assistant Examiner-Robert Saifer v Attorney-Alan Swabey [57] ABSTRACT A tow pin attachment for tow trucks. The attachment can be removably connected to a tow truck. A tow pin carried by the attachment is movable between operative and inoperative positions. Means on the tow pin lock the attachment to the truck when the tow pin is in operative position.

10 Claims, 6 Drawing Figt res PATENTEDAPR 4M2 3,653,328

sum 1 UP 2 INVENTORS Guy R. ABRAM Emil DFFERMAN PATENTEDAPR 4 i972 3 653 328 sum 2 OF 2 INVENTORS Guy R. ABRAM Emil OFFERMAN 4 rmmvhy BACKGROUND OF INVENTION 1. Field of Invention This invention relates to improvements in tow trucks.

Tow trucks are material handling platforms, carts or bins, mounted on castors. Most are equipped with a tow pin, which tow pin can be connected or disconnected with a conveyor moving under the floor of a warehouse, distribution, or shipping center. Connection of the tow pin with the moving conveyor causes the tow truck to be moved to various positions depending on the route followed by the conveyor. In more elaborate conveyor systems, means can be provided to manually or automatically switch the connected tow trucks from one conveyor line to another. The switching means can be attached to the trucks.

- 2. Description of Prior Art In the present systems, all the tow trucks, whether in use or not on the conveyor system, are equipped with tow pins and oftentimes with switching means. The cost of so equipping each of the trucks, even though all the trucks are never connected to the conveyor at the same time, is expensive. Further, there are many occasions where the user of the tow truck desires to transport the tow truck away from the conveyor system to another location. The tow pin and switching means attached to the trucks take up extra space when transported, and further, their use may not be required at the new location. The tow pins and the switching means could also be damaged during transport of the trucks from their place of use.

SUMMARY OF INVENTION It is the purpose of the present invention to provide an attachment for tow trucks, which attachment includes a tow pin and, if desired, switching means, and which attachment can be easily connected to or removed from the tow truck as required. Such an attachment provides the following advantages: when a tow truck is not in use on a conveyor system, the attachment from this truck can be removed and placed onto another truck which is going onto the conveyor system; further, when the tow trucks are to be moved or transported away from the conveyor system, the attachmentcan be easily removed from the front of the truck thus reducing the overall length of the tow truck and permitting more trucks to be transported in a given space. The removal of the attachment lessens the possibility of damage to the tow pin or switching means.

The attachment is light in weight, easily handled and can be quickly and positively connected or removed from the tow truck without requiring any special tools. The tow trucks require minimum modification to receive the attachment.

The attachment of the present invention is characterized by a brace assembly with a locking member mounted in the brace assembly for movement between a locked and unlocked position. A tow pin is mounted in the brace assembly for movement between an operative position and an inoperative position. Preferably means are provided on the tow pin for maintaining the locking member in its locked position when the tow pin is in its operative position. Means can also be provided on the tow pin for moving the locking member to its unlocked position when the top pin is moved to an inoperative position.

The invention further relates to a tow truck, modified to cooperate with the attachment. The tow truck includes locating means for receiving and positioning the attachment and means cooperating with a locking member on the attachment to positively lock the attachment to the truck.

BRIEF DESCRIPTION OF DRAWINGS The invention will now be described in detail having reference to the accompanying drawings, wherein:

FIG. 1 illustrates schematically a portion of a modified tow truck and the attachment;

FIG. 2 is a cross-section of the attachment taken along line 2-2 of FIG. 1 showing the tow pin in operative position and the attachment locked to the tow truck;

FIG. 3 is a cross-section view similar to FIG. 2 but showing the tow pin raised to an inoperative position to unlock the assembly from the tow truck;

FIG. 4 is a front elevation view of a detail of the tow pin and a portion of the brace assembly supporting the tow pin;

FIG. 5 is a plan view illustrating a further modification of the tow pin assembly allowing limited vertical movement of the tow pin when in the operative position; and

FIG. 6 is a cross-section taken along line 6-6 of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS The tow truck 1 as seen in FIG. 1 has a floor 3 and moves on castors 5 mounted at the corners of the floor. The tow truck can be of the standard type or shape now used. An attachment 7, having a tow pin 9, is connected to the tow truck. The tow pin 9 can be moved to a lower operative position to pass through a slot 11 in a warehouse floor and cooperate with a conveyor chain (not shown) running under the floor to move the tow truck as is well known. The attachment may include a bumper 13 as shown and switching devices 15 which can be programmed to switch the tow truck from'one conveyor line to another, automatically, as is well known.

Means are provided on both the tow truck and the attachment for properly positioning and locating the attachment when it is to be connected on the tow truck. As shown in FIG. I the floor 3 of the tow truck can be provided with two spaced apart holes 17, 19 adjacent its front face 21 for receiving locating pins 23, 25 mounted on a locating plate 27 attached to a brace assembly 29 of the attachment. A cutout or locating slot 31, for receiving a locating member 33 of the brace assembly 29 may also be formed in the floor of the tow truck extending in from the front face 21. A box receptacle 34 is attached to the floor of the tow truck defining an extension of the cutoff 31. Means are also provided on the truck for cooperating with means on the attachment for locking the attachment in place when it is positioned on the truck by the pins 23, 25 and the member 33. These means can comprise a slot 35 formed in the end wall 37 of the locating slot 31. The purpose of the slot 31 will be described later.

The attachment 7, carrying the tow pin 9, has a brace assembly 29 which includes a support plate 37 carrying the bumper 13, the horizontal locating plate 27 and the locating member 33 carried by the locating plate 27. The support plate 37 lies flush against the front vertical face 21 of the truck when the attachment is connected to the truck and the lower end 38 of the locating member 33 fits within the box receptacle 34. I

As shown in more detail in FIGS. 2, 3 and 4, a tow pin assembly 39, including tow pin 9,-is mounted for vertical movement in locating member 33. The locating member has a back wall 41 and side walls 43, 45. The tow pin 9 slides freely through a lower guide member which can comprise a collar 47 connected to the lower end of walls 41, 43, 45 of the locating member. Spaced upwardly from the collar 47 is an upper guide member for the tow pin 9. This can comprise an apertured plate 49 connected to walls 41, 43, 45. The tow pin assembly 39 includes the tow pin 9 and a camming head 51 connected to its upper end. The camming head can comprise a pair of cam plates 53, 55 attached, by a cross cam plate 59, to a collar 57 which slips over the upper end of the pin 9. The collar can be directly connected to the pin, if desired. The collar 57 rests on upper guide 49 and acts as a stop to prevent the pin from falling through the guides. The cam head 51 also includes a cam member 65 which can comprise a bar extending between the plates 53, 55 and positioned just above the top of tow pin 9. The cam plates 53, 55 each have a cam surface 67 on their front edge.

The plate 49 serves to locate the tow pin 9 at its correct height in relation to the conveyor when the attachment is connected to the truck and the tow pin is in its lower operative position as shown in FIG. 2. In the operative position, the lowermost end 58 of the tow pin 9 must extend'into the slot 11 to engage with a dog on the conveyor. To ensure that the lower end 59 is at the proper height, the connection between the collar 57 and pin 9 can be adjusted. A variable number of washers 61 can be placed between the top of collar 57 and a roll pin 63 is used to lock the washers in place. When using the washers 61, the collar 57 slides freely on the pin 9. The number of washers can be varied to adjust the lowermost end 58 of the tow pin to the proper height.

A U-shaped handle 69 is pivotably connected at its ends to the side walls 43, 45 of the locating member above the tow pin assembly. A crossbar 71 extends between the arms of the handle, and a link mechanism 73 (partially shown in FIG. 4), which can comprise a chain, is attached at one end to this cross bar 71 and at its other end to a bar 75 extending between the cum plates 53, 55. The bar 75 is bent to locate and maintain the chain in a central position on it as shown in FIG. 4.

Pivotably attached to the back wall 41 of the support member by a pin 85 is a locking member 79. The locking member comprises an elongated bar extending vertically down parallel to the back wall and has a locking tongue 81 at its lower end extending horizontally. The locking tongue is free to pass through an aperture 83 located in the back wall of the channelmember. At the upper end, the bar has an arm portion 87 extending away from back wall 41 into the vertical path of movement followed by the cam member 65 mounted on the cam plates.

The attachment is shown in FIG. 3 in its detached position from the cart. The handle 69 has been pivoted to an upper position where its crossbar 71 rests on the top edges 89 of the side walls 43, 45 of the locating member. A spring 91, connected at one end to the crossbar 71, and at the other end to back wall 41, maintains the handle in its upper position. In this position, the entire attachment can be easily carried about by means of the handle.

With the handle 69 in its upper position, the tow pin assembly and tow pin 9 are in a raised inoperative position, being moved there through their connection to the handle by the link 73 attached between crossbar 71 and cam head 51. In moving to its upper position, the tow pin assembly, through cam member 65 connecting arm 87 of the locking member, moves the locking member 79 to its unlocked position, thus withdt awing locking tongue out of aperture 83.

When the attachment is to be connected to the tow truck, as shown in FIG. 2, the lower end 38 of the locating member 33 is inserted in box 34 so the pins 23, 25 are aligned with the holes 17, 19 on the truck. The attachment is then lowered to place the pins in the holes until locating plate 27 is flush with the top of the cart. In this position, the locking tongue 81 is level with the slot 35 formed in the back wall 37 of the cutout 31 of the tow truck. During this positioning operation, the attachment is moved about by the handle 69 which is still in its upper position. When the plate 27 is flush on the tow truck, the handle 69 is pivoted clockwise from the upper position shown in FIG. 3 to a lower position. This then permits the tow pin 9 to drop from its upper inoperative position to a lower operative position. When the tow pin drops, cam member 65 moves down as well, releasing locking member 79. Cross cam plate 59 contacts the lower portion of the locking member 79 to move the locking member into a position where it is parallel with the back wall 33 and thus moves the tongue 81 through the aperture 83 in the back wall and through the aligned aperture 35 in the cutout of the truck. This then locks the attachment in place, the tongue 81 preventing vertical movement and the pins 23, 25 and locating member 33 preventing lateral movement.

The tow pin 9 may not move all the way down to its proper operative position when placed on the conveyor if a dog in the conveyor is passing by its lower end 58. In this case, the handle 69 rests against the cam edges 67 on the cam plates. However, once a dog on the conveyor chain moves past the tow pin, it will drop to its lowermost position, and the handle 69 will then move up the cam surfaces to a position above the top edges 93 on the plates 53, 55. Its movement is assisted by spring 91. In

this position, the handle 69 holds the tow pin in a locked position so it cannot jump out of place when the next dog on the conveyor picks it up.

To remove the attachment from the truck, it is merely necessary to pivot the handle 69 counterclockwise from the position shown in FIG. 2 to its raised position shown in FIG. 3. The cam member 65 moves upwardly with the tow pin assembly engaging the top end of the locking member 79 causing it to pivot and withdraw the tongue 81 from the apertures 83 and 35. The handle is then lifted, pulling the attachment vertically away from the tow truck.

In one embodiment of the invention, the tow pin assembly may be modified to permit limited vertical movement of the tow pin 9 when in the lower operative position. Such movement may be required when switching the tow truck from one track to another in the conveyor system. In the switching operation, the tow pin has to rise a limited amount to pass over a conveyor chain. Such limited vertical movement can be accommodated by the embodimentshown in FIGS. 5 and 6. In this embodiment, the cam head of the tow pin assembly comprises a cover 101 having two side walls 103, 105, a back wall 107 joining the side alls and a partial top wall 109 joined to the back wall and extending between the side walls. A sleeve 111 is located in an aperture in the top wall aligned with the aperture 113 in the upper guide plate 115. An extension 117 is provided on the tow pin 119 extending upwardly through the sleeve 111. The extension 117 is smaller in diameter than the tow pin 119 thus forming a shoulder 121 at their connection. A spring 123 extends between the shoulder 121 and the top wall 109. The tow pin 1 19 is prevented from dropping through the upper guide plate by a roll pin 125 and washers 127 may again be used to accurately locate the lower end of the tow pin.

The remainder of the attachment is as shown in FIGS. 2 to 4. The back wall 107 is now the cam member for operating the locking member 129 and the handle 131 is still connected by linkage to side walls 103, 105 through a bar 133. The handle 131 can be bent to clear sleeve 1 11 necessary when the handle is moved on top of side walls 103, 105.

With this arrangement, the tow pin can have limited vertical movement even when in the lower operative position to permit the tow truck to move easily from one conveyor line to another during switching. Once the tow truck has moved to the second conveyor line, the spring positively forces the tow pin down again. While the tow pin has limited vertical movement from its lower operative position to an intermediate operative position, the assembly still remains locked to the tow truck because the locking member means is not moved during the limited vertical movement of the tow pin.

If positive return of the tow pin is not desired, the spring 123 could be eliminated, and then the pin 119 would return to its lower operative position by its own weight. The sleeve 11 1 and extension 117 could also be dispensed with. The tow pin would then have limited vertical movement between the top wall 109 and its lower operative position.

We claim:

1. A readily detachable attachment for tow trucks comprismg:

a brace assembly;

a locking member mounted on said brace assembly for movement between locked and unlocked positions to lock or unlock the attachment to a tow truck;

a tow pin mounted on said brace assembly for movement between an inoperative position and an operative position; and

first means on said tow pin for maintaining said locking means in its locked position when said tow pin is in its operative position.

2. An attachment for tow trucks as claimed in claim 1, wherein the brace assembly includes a guide member for guiding movement of the tow pin between operative and inoperative positions and stop means on the tow pin cooperating with the guide member to accurately position an end of the tow pin when the tow pin is in its operative position.

3. An attachment as claimed in claim 2, wherein said locking member includes an ofiset arm portion and cam means on said tow pin, said cam means cooperating with said offset ann portion when said tow pin is moved to its inoperative position to move the locking member to an unlocked position.

4. An attachment as claimed in claim 3, wherein said first means, said stop means and said cam means comprise a unitary assembly mounted on the tow pin.

5. An attachment as claimed in claim 4, wherein said tow pin is mounted for limited movement with respect to said unitary assembly whereby the tow pin can move from its operative position to an intermediate position.

6. An attachment as claimed in claim 5, wherein a spring, connected between said tow pin and said unitary assembly, biases said tow pin to its operative position.

7. An attachment as claimed in claim 4, including movable means mounted on the brace assembly and linkage means connecting said movable means to the unitary assembly for moving the tow pin from the operative position to an inoperative position.

8. An attachment as claimed in claim 7, wherein said movable means is movable relative to the brace assembly between first and second positions, said movable means supported by said brace assembly in said first position to maintain said tow pin in said inoperative position and maintaining said tow pin in operative position when in said second position.

9. An attachment as claimed in claim 1, wherein the brace assembly includes a locating plate, and locating means on said plate for positioning the attachment on a tow truck.

10. In combination, a tow truck, said truck having a base, locating means on the base for receiving and positioning an attachment, said attachment comprising:

a brace assembly;

locating means on said brace assembly cooperating with said locating means on said base;

a locking member mounted on said' brace assembly for movement between the locked and unlocked positions;

locking member receiving means on said tow truck cooperating with said locking member when said locking member is in a locked position to lock said attachment to said truck;

a tow pin assembly including a tow pin mounted in said brace assembly for vertical movement between an upper inoperative position and a lower operative position; and

means on said tow pin assembly for maintaining said locking means in its locked position when said tow pin is in its lower operative position and for moving said locking means to an unlocked position when said tow pin assembly is raised to an upper inoperative position. 

1. A readily detachable attachment for tow trucks comprising: a brace assembly; a locking member mounted on said brace assembly for movement between locked and unlocked positions to lock or unlock the attachment to a tow truck; a tow pin mounted on said brace assembly for movement between an inoperative position and an operative position; and first means on said tow pin for maintaining said locking means in its locked position when said tow pin is in its operative position.
 2. An attachment for tow trucks as claimed in claim 1, wherein the brace assembly includes a guide member for guiding movement of the tow pin between operative and inoperative positions and stop means on the tow pin cooperating with the guide member to accurately position an end of the tow pin when the tow pin is in its operative position.
 3. An attachment as claimed in claim 2, wherein said locking member includes an offset arm portion and cam means on said tow pin, said cam means cooperating with said offset arm portion when said tow pin is moved to its inoperative position to move the locking member to an unlocked position.
 4. An attachment as claimed in claim 3, wherein said first means, said stop means and said cam means comprise a unitary assembly mounted on the tow pin.
 5. An attachment as claimed in claim 4, wherein said tow pin is mounted for limited movement with respect to said unitary assembly whereby the tow pin can move from its operative position to an intermediate position.
 6. An attachment as claimed in claim 5, wherein a spring, connected between said tow pin and said unitary assembly, biases said tow pin to its operative position.
 7. An attachment as claimed in claim 4, including movable means mounted on the brace assembly and linkage means connecting said movable means to the unitary assembly for moving the tow pin from the operative position to an inoperative position.
 8. An attachment as claimed in claim 7, wherein said movable means is movable relative to the brace assembly between first and second positions, said movable means supported by said brace assembly in said first position to maintain said tow pin in said inoperative position and maintaining said tow pin in operative position when in said second position.
 9. An attachment as claimed in claim 1, wherein the brace assembly includes a locating plate, and locating means on said plate for positioning the attachment on a tow truck.
 10. In combination, a tow truck, said truck having a base, locating means on the base for receiving and positioning an attachment, said attachment comprising: a brace assembly; locating means on said brace assembly cooperating with said locating means on said base; a locking member mounted on said brace assembly for movement between the locked and unlocked positions; locking member receiving means on said tow truck cooperating with said locking member when said locking member is in a locked position to lock said attachment to said truck; a tow pin assembly including a tow pin mounted in said brace assembly for vertical movement between an upper inoperative position and a lower operative position; and means on said tow pin assembly for maintaining said locking means in its locked position when said tow pin is in its lower operative position and for moving said locking means to an unlocked position when said tow pin assembly is raised to an upper inoperative position. 